Chagas disease, caused by the parasite Trypanosoma cruzi, affects 8 million people and imposes a major economic burden due to early mortality and physical disabilities. It is endemic in Latin America but cases are increasing in non-endemic countries, becoming a global concern. Disease progression, from symptomless to severe, are linked to parasite heterogeneity and variable host immune response. Indeed, development of robust CD8+ T cell immunity is a key element of host resistance and T. cruzi persistence and chronic Chagas disease has been associated to suboptimal CD8+ T cell responses. Consequently, defining the nature of CD8+ T cells mediating immunoprotection and the rules governing the maintenance of these cells is crucial for our understanding of the pathogenesis of Chagas disease and also for the design of novel therapeutic and vaccination approaches. Cytokines are central environmental cues that dictate the magnitude and quality of protective CD8+ T cell responses and, thus, emerge as attractive targets for immunointervention. However, our incomplete knowledge about the cytokines, signaling pathways and transcriptional programs involved in the generation of optimal CD8+ T cell immunity holds back possible applications of relevance to human health. Our compelling preliminary findings show that IL-17RA-signaling cytokines are critically involved in the regulation of the developmental pathways that determine the generation of robust protective CD8+ T cell responses to T. cruzi. Using phenotypic, functional and genomic profiling we propose to dissect the mechanisms underlying IL-17RA-mediated regulation of specific CD8+ T cell development. Adoptive transfer experiments together with in vitro culture approaches will be used to establish whether IL-17RA-signaling plays CD8+ T cell intrinsic and/or extrinsic roles in supporting CD8+ T cell immunity. Finally, genetic vaccination and cytokine-based treatment will help to determine the potential therapeutic use of IL-17A to boost CD8+ T cell immunity to T. cruzi during natural infection and vaccination. Our studies will provide meaningful data about the role of IL-17RA-signaling cytokines in the regulation of CD8+ T cell immunity to T. cruzi, providing potential new targets for the rational design of therapies for Chagas disease and, likely, other chronic infections. We also expect to identify the cellular and molecular programs triggered by IL-17RA-signaling and how they dictate particular CD8+ T cell fates. This knowledge will profoundly impact on fundamental immunology and may provide a rationale for understanding unsuspected effects of IL-17-targeted therapies during human diseases.